Yes, I do tend to look through the lense of the Judeo-Christian tradition -- seems like that's what's thrown up most as a block to progressive social change in Modern America. The cultural roots you mention are interesting, though. It's interesting to think about what role, for example, hostility to Greek cultural may have played.
Still, the taboo is nearly universal. Look at Africa. Sure, they're spurred on by the continuing flood of "Christian" missionaries preaching violence and hatred, but the Family and others seem to find very fertile grounds for their "teachings" there. I think that speaks to an organic psychological mistrust of non-standard sexuality in general, and I relate that to a fear for the family structure -- a loss of parents to outside interests and so forth.
Of course, the clearest proof that hatred of homosexuality had nothing to do with having children relates to the fact that homosexuals did have kids--and still got in trouble. There were plenty of married husband and wives, fathers and mothers, having gay sex on the side--and they still got stoned for that. So even those who were married, had done their duty, and were still doing their duty of obeying the Bible's rule to multiply ended up being killed for having gay sex.
I think this actually reinforces my original thought. Homosexuality wasn't traditionally a parallel to heterosexual, family-raising sexuality. It existed as something done on the side, or in addition to. Off the books, so to speak. Somewhere along the line, someone felt threatened by this. Perhaps a few soldiers were spending too much time with their "comrades" and not enough with the children. Perhaps it became too open a practice, threatened to "speak its name" so to speak. But it never went away -- just back underground. Where empowered groups like things outside the norm to stay.
Or, do you know of a tradition similar to what at least a segment of the gay population is looking for today -- monogamous, long-term family structure? That seems like a new idea, and thus, a new threat. Silly as it is, I think one of the babbling, insane voices of society's inner pscyhe keeps saying "What if EVERYONE was gay and entered into gay marriage? How we will continue to exist?" This kind of slippery slope thinking misinforms a lot of arguments today ("if they can take away one kind of gun ...") etc.
Stepping back from that element -- which I still believe plays a role -- I think we're now dealing with a more familiar pattern in America of people simply wanting an underclass -- someone to look down on. To have groups with an inherent, irreversible lack of power to occupy the lower rungs. I'm thinking now of the rage of Southern whites watching the first black students show up for school in Alabama. That's a rage born of *entitlement*. These were (and are) people who believe in the "zero-sum" notion of social power. If you have more, I must have less. It couldn't be more wrong, but the idea holds a lot of power.
I come to this in part based on what I perceive as a willingness by conservative groups to accept the existence of homosexuality, as long as it remains a hidden "sin," rather than an acceptable human mode. Thus all the claims of a "gay agenda" to "shove it down our throats" and so forth. "It's not that you're gay, it's that you're failing to lie about it, and thus elevating yourself from the underclass."
What they'd like, as in so many circumstances, is for everyone to agree upon a lie. Like the Iranian leader hilariously declaring that there is no homosexuality in Iran, when the obvious truth is that there is no OPEN homosexuality in Iran, because homosexuals there are afraid, which is the way they like it. The message is "Be different, but be afraid."